Demodulation table, demodulating device and demodulating method, program, and recording medium

Abstract

A demodulation table for converting variable length code (d, k; m, n; r) is provided. The variable length code has a maximum constraint length r>1, has a minimum run of d (d>0), has a maximum run of k, and a basic codeword length of n bits into data having a basic data length of m bits. The demodulation table includes: a basic table for converting code patterns composed of basic codes having a basic codeword length of n bits into data patterns composed of basic data having a basic data length of m bits; and a substitution table for converting code patterns of a plurality of different minimum run successive occurrence limiting patterns determined so as to limit successive occurrences of the minimum run to a maximum of N (N>1) times into a corresponding identical data pattern.

1. A demodulation table for converting variable length code (d, k; m, n; r) having a maximum constraint length where r>1, having a minimum run of d, where d>0, a maximum run of k, and a basic codeword length of n bits into data having a basic data length of m bits, said demodulation table comprising:
 a basic table for converting code patterns composed of basic codes having a basic codeword length of n bits into data patterns composed of basic data having a basic data length of m bits; and 
 a substitution table for converting code patterns of a plurality of different minimum run successive occurrence limiting patterns determined so as to limit successive occurrences of said minimum run to a maximum of N times into a corresponding identical data pattern, where N>1. 
 
   
   
     2. The demodulation table according to  claim 1 ,
 wherein the data pattern corresponding to the code pattern of said minimum run successive occurrence limiting pattern includes a data pattern corresponding to the code pattern of another said minimum run successive occurrence limiting pattern as a part of the data pattern. 
 
   
   
     3. The demodulation table according to  claim 1 , further comprising a substitution table for converting code patterns determined so as to limit said maximum run to M into corresponding data patterns, where M>0. 
   
   
     4. The demodulation table according to  claim 3 ,
 wherein d=1, k=7, m=2, and n=3, and a number of successive occurrences of said minimum run is not greater than five. 
 
   
   
     5. A demodulating device for converting variable length code (d, k; m, n; r) having a maximum constraint length r>1, having a minimum run of d, where d>0, a maximum run of k, and a basic codeword length of n bits into data having a basic data length of m bits, said demodulating device comprising:
 first converting means for converting an input codeword string into a data string according to a first demodulation table including basic code patterns and basic data patterns associated with the basic code patterns; 
 second converting means for converting an input codeword string into a data string according to a second demodulation table including code patterns of a plurality of different minimum run successive occurrence limiting patterns determined so as to limit successive occurrences of said minimum run to a maximum of N times, where N>1, and an identical data pattern associated with the code patterns; 
 first detecting means for detecting the code patterns of said minimum run successive occurrence limiting patterns; and 
 selecting means for selecting the data string converted according to said second demodulation table when said minimum run successive occurrence limiting pattern is detected. 
 
   
   
     6. The demodulating device according to  claim 5 ,
 wherein said selecting means selects a data string converted according to a basic code pattern in a minimum unit and a basic data pattern associated with the basic code pattern. 
 
   
   
     7. The demodulating device according to  claim 5 , further comprising codeword string converting means for generating said codeword string from an input signal. 
   
   
     8. The demodulating device according to  claim 5 ,
 wherein said first demodulation table further includes code patterns determined to limit the maximum run to M, where M>0, and data patterns associated with the code patterns. 
 
   
   
     9. A demodulating method for converting variable length code (d, k; m, n; r), having a maximum constraint length r>1, having a minimum run of d, where d>0, a maximum run of k, and a basic codeword length of n bits into data having a basic data length of m bits, said demodulating method comprising:
 converting an input codeword string into a data string according to a first demodulation table including basic code patterns and basic data patterns associated with the basic code patterns; 
 converting an input codeword string into a data string according to a second demodulation table including code patterns of a plurality of different minimum run successive occurrence limiting patterns determined so as to limit successive occurrences of said minimum run to a maximum of N times, where N>1, and an identical data pattern associated with the code patterns; 
 detecting the code patterns of said minimum run successive occurrence limiting patterns; and 
 selecting the data string converted according to said second demodulation table when the code pattern of a said minimum run successive occurrence limiting pattern is detected. 
 
   
   
     10. A computer program product embodied on a computer readable medium for converting variable length code (d, k; m, n; r) having a maximum constraint length r>1, having a minimum run of d, where d>0, a maximum run of k, and a basic codeword length of n bits into data having a basic data length of m bits, said program causing a computer to perform:
 a first converting step of converting an input codeword string into a data string according to a first demodulation table including basic code patterns and basic data patterns associated with the basic code patterns; 
 a second converting step of converting an input codeword string into a data string according to a second demodulation table including code patterns of a plurality of different minimum run successive occurrence limiting patterns determined so as to limit successive occurrences of said minimum run to a maximum of N (N>1) times and an identical data pattern associated with the code patterns; 
 a detecting step of detecting the code patterns of said minimum run successive occurrence limiting patterns; and 
 a selecting step of selecting the data string converted according to said second demodulation table when the code pattern of a said minimum run successive occurrence limiting pattern is detected. 
 
   
   
     11. A recording medium on which the program of  claim 10  is recorded. 
   
   
     12. A demodulating device for converting variable length code (d, k; m, n; r) having a maximum constraint length r>1, having a minimum run of d, where d>0, a maximum run of k, and a basic codeword length of n bits into data having a basic data length of m bits, said demodulating device comprising:
 a first converter for converting an input codeword string into a data string according to a first demodulation table including basic code patterns and basic data patterns associated with the basic code patterns; 
 a second converter for converting an input codeword string into a data string according to a second demodulation table including code patterns of a plurality of different minimum run successive occurrence limiting patterns determined so as to limit successive occurrences of said minimum run to a maximum of N (N>1) times and an identical data pattern associated with the code patterns; 
 a first detector for detecting the code patterns of said minimum, run successive occurrence limiting patterns; and 
 a selector for selecting the data string converted according to said second demodulation table when a said minimum run successive occurrence limiting pattern is detected. 
 
   
   
     13. A demodulation table for converting variable length code (d, k; m, n; r) having a maximum constraint length where r>1, having a minimum run of d, where d>0, a maximum run of k, and a basic codeword length of n bits into data having a basic data length of m bits, said demodulation table comprising:
 a basic table for converting code patterns composed of basic codes having a basic codeword length of n bits into data patterns composed of basic data having a basic data length of m bits; and 
 a substitution table for converting code patterns of a plurality of different minimum run successive occurrence limiting patterns determined so as to limit successive occurrences of said minimum run to a maximum of N times into a corresponding identical data pattern, where N>1, wherein said demodulation table has a conversion rule that a remainder when a number of “1”s within said data pattern is divided by two and a remainder when a number of “1”s within said code pattern is divided by two both be one of 1 and 0, and thus match each other. 
 
   
   
     14. A demodulating device for converting variable length code (d, k; m, n; r) having a maximum constraint length r>1, having a minimum run of d, where d>0, a maximum run of k, and a basic codeword length of n bits into data having a basic data length of m bits, said demodulating device comprising:
 first converting means for converting an input codeword string into a data string according to a first demodulation table including basic code patterns and basic data patterns associated with the basic code patterns; 
 second converting means for converting an input codeword string into a data string according to a second demodulation table including code patterns of a plurality of different minimum run successive occurrence limiting patterns determined so as to limit successive occurrences of said minimum run to a maximum of N times, where N>1, and an identical data pattern associated with the code patterns; 
 first detecting means for detecting the code patterns of said minimum run successive occurrence limiting patterns; 
 selecting means for selecting the data string converted according to said second demodulation table when said minimum run successive occurrence limiting pattern is detected; and 
 second detecting means for detecting a code pattern including the code pattern of at least one said minimum run successive occurrence limiting pattern as a part of the code pattern, 
 wherein said selecting means selects one of data strings converted according to a first part of said first demodulation table and a second part of said first demodulation table using a result indicating whether a code pattern including the code pattern of one said minimum run successive occurrence limiting pattern as a part of the code pattern is detected. 
 
   
   
     15. A demodulating device for converting variable length code (d, k; m, n; r) having a maximum constraint length r>1, having a minimum run of d, where d>0, a maximum run of k, and a basic codeword length of n bits into data having a basic data length of m bits, said demodulating device comprising:
 first converting means for converting an input codeword string into a data string according to a first demodulation table including basic code patterns and basic data patterns associated with the basic code patterns; 
 second converting means for converting an input codeword string into a data string according to a second demodulation table including code patterns of a plurality of different minimum run successive occurrence limiting patterns determined so as to limit successive occurrences of said minimum run to a maximum of N times, where N>1, and an identical data pattern associated with the code patterns; 
 first detecting means for detecting the code patterns of said minimum run successive occurrence limiting patterns; 
 selecting means for selecting the data string converted according to said second demodulation table when said minimum run successive occurrence limiting pattern is detected; and 
 extracting means for removing one of a synchronizing pattern and a Digital-Sum-Value control bit inserted at a predetermined position from the data string selected by said selecting means, and extracting data bits. 
 
   
   
     16. A demodulating device for converting variable length code (d, k; m, n; r) having a maximum constraint length r>1, having a minimum run of d, where d>0, a maximum run of k, and a basic codeword length of n bits into data having a basic data length of m bits, said demodulating device comprising:
 first converting means for converting an input codeword string into a data string according to a first demodulation table including basic code patterns and basic data patterns associated with the basic code patterns; 
 second converting means for converting an input codeword string into a data string according to a second demodulation table including code patterns of a plurality of different minimum run successive occurrence limiting patterns determined so as to limit successive occurrences of said minimum run to a maximum of N times, where N>1, and an identical data pattern associated with the code patterns; 
 first detecting means for detecting the code patterns of said minimum run successive occurrence limiting patterns; 
 selecting means for selecting the data string converted according to said second demodulation table when said minimum run successive occurrence limiting pattern is detected; and 
 synchronizing pattern detecting means for detecting a synchronizing pattern inserted at a predetermined position from the input said codeword string.